The illumination of a lamp assembly may be controlled using standard phase cut dimmers, thereby signaling dimming information in the form of a conduction angle to the lamp assembly. Phase cut dimmers may operate in different modes such as leading edge dimmers or trailing edge dimmers. There are however some challenges regarding stable dimming and illumination control for lamp assemblies that dissipate only little power. For instance, some phase cut dimmers require a minimum load and may exhibit false firing and flickering, especially at low diming levels. Moreover, different characteristics of different types of dimmers and lamps assemblies are to be taken into consideration. A clear distinction between different dimming modes is sometimes difficult to achieve. Further, different characteristics (e.g. non-linearity, transient periods, etc.) associated with different dimming curves should be taken into account.
The Digital Load-Side Transmission (DLT) lighting control specification defined by IEC 62756 and U.S. Pat. No. 8,217,589 B2 describe the superposition of a small amplitude modulated (AM) baseband signal on the mains voltage by a control device (e.g. a dimmer switch) in order to control the illumination of connected lamp(s). A protocol is specified to control brightness/intensity, color, color temperature and other parameters for lighting sources such as CFL, LED, etc. The effective transmission rate for conveying lamp control data is 200 bit/s at 50 Hz and 240 bit/s at 60 Hz. Other digital data modulation power line communication techniques for controlling the operation of a lamp assembly are also available and within the scope of the present document.